Sound-direction-determining apparatus



June 3, 1930. c. VON HOFE 1,762,102

SOUND DIRECTION DETERMINING APPARATUS Filed April 18, 1928 ll nr'q 1177/:

Patented June 3, 1930 I UNITEDSTATES PATENT o FicE CHIRISTIAN VON HOFE, F VIENNA, AUSTRIA, ASSIGNOR TO 0. P. GOERZ OPTISUHE AN- STALT AKTIENGESELLSCHAFT, AKCIOVA SPOLECNOST K. P. GOERZ OPTICKY USTAV, OF BRATISLAVA, GZEGHOSLOVAKIA, A CZEGHOSLOVAK COMPANY SOUND-DmECTION-DETERMINING APPARATUS Application filed Apr-i118, 1928, Serial No. 271,006, and in Germany May 7, 1927.

In sound direction determining apparatus for finding invisible aircrafts and which, according. to the prior Patent No. 1,649,538, consists of bodies of revolution confooally connected with each other and serving as These disturbances may be prevented according to the invention-by providing the sound leading reflectorsrwith one or more longitudinal slots preferably inthat plane which takes the least part in the reflection of the sound, that is to say'the meridian plane perpendicular to the acoustic axis of the preceding reflector which 'slots may be covered with some soft material such as 5 leather, rubber balloon fabric and the like cemented thereover, for preventing rain, snow, dust and the like from penetrating.

In the drawing,'asan example of construction a sound direction determining apparatus is shown which is designed for finding targets, moving on the ground. Fig; 1' is a plan view of the sound direction determining apparatus, Fig. 2 is a transverse section of one ofthe sound leading reflectors.

The sound'direction determining apparatus shown has two receiving reflectors a and b and two sound leading reflectors c and d. The first named reflectors are shaped as obliquely cut paraboloids while the last named .reflectors'are in the shape of ellipsoids. One of the receiving reflectors and one of thesound leading reflectors are so connected with each other that the focus of the paraboloid coincides with the outer focus of the ellipsoid. At each ofthe inner foci of the ellipsoids is located either a microphone or the ear of the sound observer. The two ellipsoids c and d'withthe paraboloids a and b are rotatably mounted m a yoke I 50 fixed to an upright e, the one a being rotatbeing rotatable around a pivot h.

A screw rotatably mounted in the up right-e serves for adjusting the reflectors around the pivots g and h. Each of the ellipsoids isprovided with two longitudinal slots j, located in a plane perpendicular to the plane determined by the axes A,' A, B, B, C, C, of the reflectors in the example shown in a vertical plane.

able around a pivot g, and the other, d,

- The slots 7' may be covered by strips of" rubber or the like cemented thereover for preventing rain, snow, dust-and soon from penetrating into the reflectors.

. What I claim is: p i

1." A sound direction determining apparatus comprising at least one sound receiving reflector formed of a paraboloid of revolution and at least one sound leading reflector in the form of an elongated ellipsoid of revolution, the said paraboloid and ellipsoid of revolution being confocal, and the sound leading reflector being provided with at least one slot extending in a meridian plane. 2. A sound direction determining apparatus comprising at least one sound receiving reflector formed of a paraboloid of revolution and at least one sound leading reflector in the form -of an elongated ellipsoid of revolution, the said paraboloid and ellipsoid of revolution being confocal, and the sound leading reflector/ being provided with at least one slot extending in a meridian plane perpendicular to the acoustic axis of the preceding reflector.

3. A sound direction determing apparatus comprising at least one sound receiving reflector formed of a paraboloid of revolution and. at least one sound leading reflector in the form of an elongated ellipsoid of revolution, the said paraboloid and ellipsoid of revolution being confocal, and the sound leading reflector being provided with at least one slot extending in a meridian plane, the said slot being covered by a sheet of soft material.

In testimony whereof I have aflixed my signature. I

. CHRISTIAN voN HOEE. 

